Roller and track configuration for a tripod joint

Abstract

A tripod joint has an outer joint part (1, 41, 61) with three circumferentially distributed longitudinal recesses (2, 42, 62) each forming circumferentially opposed tracks (4, 5; 45, 65). An inner joint part (7, 47, 67) with tripod arms (9, 49, 69) which extend into the longitudinal recess (2, 42, 62) is positioned within the outer joint part (1, 41, 61). Rolling members (10, 50, 70) in rolling contact with the tracks (4, 5; 45, 65) are supported and movably and pivotably held on the tripod arms (9, 49, 69). The longitudinal recesses (2, 42, 62) include guiding means (18, 19) holding the rolling members (10, 50, 70) in the longitudinal recesses (2, 42, 62) so as to be axis-parallel with the joint. The rolling member (10, 50, 70) are in contact with one of the tracks (4, 5,; 45; 65). In each case, there is provided a first contact point (C) for accommodating a circumferentially extending transmission force F R in the region of a central roller plane (E) and at least one second contact point (A) for accommodating an inwardly directed guiding force F F in the region of a radially inner supporting shoulder (19).

We claim: 
     
       1. A tripod joint comprising: an outer joint part with three circumferentially distributed longitudinal recesses each forming circumferentially opposed tracks;   an inner joint part with three tripod arms which extend into the longitudinal recesses, respectively;   a plurality of three rolling members supported by and movably and pivotally held on said tripod arm in rolling contact with said tracks;   the longitudinal recesses being provided with guiding means for holding and guiding the rolling members in said longitudinal recesses, said guiding means associated with and extending parallel to said longitudinal recesses such that said rolling members are axis-parallel to themselves throughout their rolling contact with said tracks, and said rolling members being in contact with one of said tracks such that there is provided a first contact point with said tracks for accommodating a circumferentially directed transmission force in the region of a central roller plane and at least one second contact point with said guiding means spaced from said first contact point for accommodating an inwardly directed guiding force, said second contact point being on a surface of the associated one of said guiding means and said guiding means surface on an acute or obtuse angle with respect to the arm axis;   said first contact point being different from said second contact point and with contact existing in both the first and second contact points when said inwardly directed guiding force is exerted from said tripod arms to said rolling members.   
     
     
       2. A tripod joint according to claim 1, wherein said rolling members are in contact with one of the tracks such that there is provided a further third contact point for accommodating a radially outwardly directed guiding force of said guiding means, said third contact point being different from said first and second contact point with contact existing in both the first and third contact points when an outwardly directed force is exerted from said tripod arms to said rolling member. 
     
     
       3. A tripod joint according to claim 2, wherein said rolling members alternately contact with play between the second and third contact points. 
     
     
       4. A joint according to claim 2, wherein said third contact point, with respect to the arm axis, is positioned radially outside the first contact point, and as far as distance and position relative to said first contact point is concerned, said third contact point is arranged approximately symmetrical with the second contact point. 
     
     
       5. A joint according to claim 1, wherein a tangential plane on the roller and track surfaces at said first contact point extends perpendicularly relative to said central roller plane. 
     
     
       6. A tripod joint according to claim 1, wherein a tangential plane on the roller and track surfaces at said first contact point, while opening outwardly, extends at an angle relative to a reference plane which itself extends perpendicularly relative to the central roller plane, thereby causing an outwardly directed reaction force exerted from said tripod arms on the rollers. 
     
     
       7. A joint according to any claim 1, wherein said first contact point is provided between a cylindrical roller surface and a track surface which is convex when viewed in cross section through said joint. 
     
     
       8. A joint according to claim 7, wherein the radius of curvature of the track surface is greater than the roller radius. 
     
     
       9. A joint according to claim 1, wherein said first contact point is provided between a roller surface, which is convex when viewed in a cross section through the joint, and said track surface being planar. 
     
     
       10. A joint according to claim 9, wherein the radius of curvature of the roller surface is greater than the roller radius. 
     
     
       11. A joint according to claim 1, wherein said first contact point is provided between a roller surface, which is convex when viewed in cross section through the joint, and said track surface is convex when viewed in cross section through said joint. 
     
     
       12. A joint according to claim 11, wherein the radius of curvature of the roller surface and/or the radius of curvature of the track surface in cross section through the joint is greater than the roller radius. 
     
     
       13. A joint according to claim 1, wherein said second contact point, with respect to the arm axis, is located radially inside the first contact point and a tangential plane between said two points inclined at an angle of approximately 45° relative to the arm axis. 
     
     
       14. A joint according to claim 1, wherein said rolling member includes a rolling contact bearing supporting said rolling member, said rolling member runs on a roller carrier which is held on said tripod arm so as to be radially movable and pivotable and that said roller carrier includes a cylindrical bore engaged by a spherical arm end of said tripod arm. 
     
     
       15. A joint according to claim 1, wherein said rolling member includes a rolling contact bearing supporting said rolling member, said rolling member runs on a roller carrier which is held on said tripod arm so as to be radially movable and pivotable and that the roller carrier is designed to be in two parts and includes an internally spherical outer ring which is pivotable on an externally spherical inner ring, the latter, with an internally cylindrical bore, being movable on a cylindrical end of said tripod arm. 
     
     
       16. A joint according to claim 1, wherein said rolling member includes an internally cylindrical bore engaged by an externally spherical inner roller which, while being supported by a rolling contact bearing, runs on said tripod arm.